Manufacture of phenol



T. BEwLEY ET Al.

MANUFACTURE oF PHENOL Filed April e. ma

Dec. 22, 1953 Patented Dec. 22, 1953 t .LIAQZEURE QF BEEN!!! *Thomas K:Bowlen 'f-Epsom, and Frederick John fWilkins, :Epsom "Doivns, England, v aSSigIlors to lloroules -fliorrder-folinmnn a corporation of allentrareV fClz/tinismriotitr, applica-tion.:tirent-Britain Ysoleil 20, .1354.3

i12 Glaims.

'itl-iis invention .relates :t9 on :iro-proved process for t .emenufaoture-ofphetid.and refers inpertieulerto the step Qiits reooverrirom `its solution itsonropyllbtnzene. $11,611 mirto-res are ebt ed iorginstenoe isopronrlbenzenenrdroperoxide dissolved isopropyl traitent treated wtheoid stroll suivront aoidin order torroduoephenolanfi eoetonehr the doomrosition lof .solo :isOPrQllfl tenzone 'lirtlroeeroxidof Thisneroxidein its 'tiirttmay :be prodotto by the oxidation oi, isoprqrpizbenterieintlioiliouidilhase bri-means. .oi Iioleoiilar Qreenat elevated itemfrrooesses of this .rotore :have :been described in co-pendinglgS. A. lpatent applications Serial No. 5,1'7,ill egt, lanuary 21, 1948, now U. vS. Patent No. 2,628,983, Serial No. 15,954, filed March `19, 11.948, mow 2U. Patent No. 25632,i1f12, andiSerialriNo. A5,326,.led August 20, i948.

-rI-t has 4been .found that besides `phenol and acetone as .main .products the reaction mixture resulting `from :the decomposition -step contains also .small amounts fof aeetophenone .and methyl styrene.' These substances cause diculties --in the .separation and the isolation lof :the-phenol and .in .the .reuse of sthe nnreacted isopropyl -ben- .zene -for the lsan'letprocess of .-oxidising it to its peroxide.

'Inspite of the-considerable differ-ences in their boiling points-isopropyl ibenzene boils at 1115.29 C. and phenol at 182 complete vvseparation by distillation is diiiicult and requires the use ofthigh reflux `ratios necessitating thereby Jthe consumption lofflargeqnantitieeofsteam,large distillation columns, condensers and `the :like -Moreover,

practically complete separation of the -phenol from the acetoph-enone also present and fthe -recoveity of the 4itl'icle Aof the-phenol in a substantiall-y pure -state by .distillation fis not possible since these two .substances form -a constant vflooiling mixture. The presenee -oi acetophenone in the phenol even in `small amounts detracts coneiderably V`from the vtrahie of the latter substance.

The r re-.use of lthe unchanged isopropyl 4benzene onthe other hand, -isfimportant for the economie success of -the process of mrnarm-ifaoturing phenol and acetone by the said method, especially as, on .account of the incipient decomposition of the peroxidiccompounds already-formed when a certain limit of their concentration in the A'liquid mixture is exceeded, ithas vlbeen -founcl expedient to 'terminate the oxidation when aboutf2'0 to 25 percent of the isopropyl benzene Ihas Vbeen con- `Vertedinto the corresponding peroxide. Onvsubjeoting this mixture `to a. heatftreatment ivf/ith acid in order -to decompose vthe peroxide contained therein and :form radio1 `the .admired 180 to percent ef isopropyl'benzene whichreinained reaotesi noon tlor the .Qiyeeo here to be recycle@ to the oxidation stage after the phenol Ihaga,been recovered therefrom. Any phenol left in the iso- 'f2 propylbenzeneenet only reduces-the -yield of the valuable product as it is destroyed-inthe con-rse of the subsequent oxidation step to which the isopropyl l benzene is recycled,A -butalso impairs the efliciency of the oxidation process itself.

It is an object of--the present inventionl-oprotvide a simple process by which the phenol is obtained substantiallyv-uncontaminated -by acetof phenone, anllby which the phenolis recovered as completely as'fpossible. Itis a YVfurther object of the invention tol-recover ,the unreacted jsop-ropyl benzene substantial-ly free-irom phenol,so that after removal of the -acetophenone and methyl styrene admired therewith `the isopropyl benzene may `be recycled l:for further oxidation to its-peroxide. c

Accordinglythe-inrentionprovidesiinthemanufacture ofhphenol 'by the oxidation vof'*isopropyl benzene into isopropyl benzene 'hyd-roperox'ide and `the decomposition of said hydroperoxide in its `'solution in unchanged isopropyl v:benzene into a mixture containing phenol,acetone'y acetophenone and methyl styrene, the step of recovering the phenol substantially `free from acetophenne which comprises extracting said mixture Wit Water atv `teniperotin-es between 50" Cqand 169 and recovering the phenol from the al'lueous extract. y

The extraction with water 'according to v'this invention'is carried ontpreferably afterthe acetone has been rernoved-irorn the reaction I nixture forinstance by distillation. '.Ihe preferred temperature orthe vwater v4for the extraction is between and 80` C. Thevwa'ter dissolyegsl'prae-` tieally all ithe phenol which can be recovered therefrom l'by `any suitable method, -for instance by extraction with a preferential solvent `f or phenol, such Ias vbutyl acetate or diisopropyl ether. e

The extraction byrneans of Water is advantageously carried -out by contacting the mixture resulting -from the decompositionv of isopropyl benzene hydroperoxide preferably after the remora'l of .the vacetone with a countercurrent stream .of `water Afor `instance -fi-n y.a packed tower or eby any ,other ci the .weilflanown methodsof such purification the isopropyl benzene is suiciently pure to be subjected to the oxidation process in order to produce therefrom its hydroperoxide which may then be decomposed for the manufacture of phenol. It is therefore an additional feature of the present invention to recycle the isopropyl benzene after the purication to the oxidation stage.

Any small quantity of phenol which may be left behind in the isopropyl benzene-after the extraction with hot water may if so desired be removed by an additional extraction with aqueous alkali metal hydroxide solution. In most cases however the amount of phenol left behind in the isopropyl benzene is so small that it will not cause any material disadvantage in a technical or economic respect.

The attached diagram and the example illustrate the method by which the process of the invention may be carried out in practice, the

percentages given being by weight.

The reaction mixture coming from the reactor in which the decomposition of the isopropyl benzene peroxide in isopropyl benzene by means of for instance, sulphuric acid has been eected f at a temperature of about 150 C. to the base of :'i'

a packed tower 2 and iiows upwards through the tower in countercurrent to a descending stream of hot water pumped to the top. The temperature of this water is adjusted by heat exchangers 3 and 4 to maintain the temperature of approxiric mately 70 to 80 C. in the tower 2. In this tower the bulk of the phenol with very little of the acetophenone passes into the aqueous phase while the oil phase containing mainly isopropyl benzene substantially free from phenol but still containif ing the bulk of the acetophenone overflows from the top of the tower 2 at 51 This oil phase is then subjected to distillation in column Il to remove the acetophenone. After treatment for removal of methyl styrene by hydrogenation in reactor I8 the isopropyl benzene may then be recycled to the oxidation reactor.

The aqueous solution of phenol containing a little acetophenone flows from the base of the extraction tower 2 through a heat exchanger 6 in which it is cooled to about 30 C. and is then pumped through further cooler 'I to the top of a second packed tower 8 which it enters at about 20 C. In this tower it is contacted with a countercurrent stream of butyl acetate or other suitable solvent pumped from a storage tank 9 into the base of the tower. The butyl acetate extracts substantially all the phenol and the small quantity of acetophenone from the aqueous solution to give a concentrated extract which overows from the top of the tower 8 at I 0 to the distillation column II, and from the top of this column the butyl acetate is distilled off and flows to tank 9. Phenol, substantially free from acetophenone, is taken oi as a vapour from an intermediate point in the column II to a condenser l2 from which it flows to storage. The residue which flows to waste from the base of column II consists of the small amount of acteophenone present Y Y in the butyl acetate extract together with a very small quantity of phenol.

Alternatively the whole of the phenol, together with its small admixture of acetophenone can be taken off as a residue from the base of column II and passed to a further column in which the phenol is taken off as a distillate and the small amount oi acetophenone together with a little phenol is discharged as a residue.

The water leaving the base of the second extraction tower B is saturated with butyl acetate. It ilows through heat exchanger B in which its temperature is raised to about 60 C. and then through a second heat exchanger I3 in which its temperature is further raised to about 90 C. and thence to a distillation column I4'. From this column the butyl acetate is distilled off as its constant boiling mixture with water and ows to a condenser I5 and decanter I6 from which the water is taken back to the top of distillation column I4 and the butyl acetate flows to tank 9. The stripped water from the base of said column I4 passes through heat exchanger I3 Where it is cooled to about 70 C. and is then pumped to the top of the iirst extraction tower 2. Its temperature is adjusted to maintain the required temperature of '70 to 80 C. in the tower 2 by passage through heat exchangers 3 and 4 in which it can be either heated by steam or cooled by cold water.

Example 71.6 lbs/hr. of a mixture resulting from the oxidation of isopropyl benzene and decomposi-` tion of the peroxide with aqueous sulphuric acid, and containing 9.1% of acetone, 15.2% phenol, 0.84% acetophenone, 1.5% methyl styrene and the remainder isopropyl benzene, was fed to a distillation column to separate the acetone. The

,X resulting acetone-free liquid, 65.1 lbs./hr., con- .sol

tained 16.7% phenol, 0.92% acetophenone, 1.7% methyl styrene and the remainder isopropyl benzene. It was fed to the base of a packed column which was maintained at a temperature of approximately 70-80 C. and to the top of which was admitted 417 lbs/hr. of water at about r10" C.

Approximately 98% of the phenol and only 25% of the acetophenone was extracted from the isopropyl benzene to give 427.8 lbs/hr. of an aqueous solution containing 2.5% phenol and 0.035% acetophenone. The extracted isopropyl benzene,` after distillation to separate acetophenone, and treatment to remove methyl styrene, was recycled to the oxidation stage of the process.

The aqueous extract was cooled to 20 C. and admitted to the top of a second packed col-umn. Into the base of this column was fed 18 lbs/hr. of butyl acetate. Approximately 99% of the phenol was extracted from the aqueous solution to give 26.6 lbs/hr. of an extract containing 40% of phenol and substantially all of the acetophenone from the aqueous solution. The extracted aqueous solution from the base of the column contained approximately 0.5% butyl acetate and after distillation to recover this butyl acetatewasused again for extraction in the iirst tower.

The butyl acetate extract containing 40% of phenol was distilled to recover 15.9` lbs/hr. of butyl acetate which was used again in the extraction process. The residual 10.6 lbs/hr. of phenol plus 0.15 lb./hr. of acetophenone was distilled to give a distillate of 10.55 lbs/hr. of phenol substantially free from acetophenone and a residue of 0.15 lb./hr. acetophenone plus 0.05 lb./hr. of phenol.

We claim:

1. In the maufacture of phenol by the oxidation of isopropyl benzene into isopropyl benzene hydroperoxide and the decomposition of said hydroperoxide in its solution in unchanged isopropyl benzene to form phenol, said solution also containing acetophenone, acetone and methyl styrene, the step of substantially separating the phenol from said acetophenone, acetone and methyl styrene which comprises extracting the reaction mixture with water at temperatures between 50 and 100 C. and recovering the phenol from the aqueous extract.

2. Process according to claim 1, wherein the temperature is between '70 and 80 C.

3. Process according to claim l, wherein the water extraction is effected after removal of the acetone.

4. Process according to claim 3, wherein the acetone is removed by distillation.

5. In the manufacture of phenol by the oxidation of isopropyl benzene into isopropyl benzene hydroperoxide and the decomposition of said hydroperoxide in its solution in unchanged isopropyl benzene to form phenol, the step of recovering the phenol from said solution containing in addition acetone and methyl styrene which comprises extracting the reaction mixture with water at temperatures between 50 and 100 C. and recovering the phenol from the aqueous extract by contact with an organic solvent which is substantially immiscible with water and a solvent for phenol, and subsequent distillation.

6. Process according to claim 5, wherein after the extraction with water any residual phenol is removed from the unchanged isopropyl benzene by washing with aqueous alkali metal hydroxide solution.

7. Process according to claim 6, wherein the unchanged isopropyl benzene after the substantially complete removal of phenol therefrom is substantially freed from acetophenone and methyl styrene before it is recycled to the oxidation stage.

8. In the manufacture of phenol by the oxidation of isopropyl benzene into isopropyl benzene hydroperoxide and the decomposition of said hydroperoxide in its solution in unchanged isopropyl benzene to form a solution containing phenol, acetophenone, acetone and methyl styrene as well as unreacted isopropyl benzene, the process of recovering the latter substantially free from phenol, acetophenone, acetone and methyl styrene, whereby the thus-purified unreacted isopropyl benzene may be recycled for further oxidation into isopropyl benzene hydroperoxide without impairing the efciency of the oxidation due to prejudicial impurities, said process comprising removing the acetone from said lastnamed solution by distillation, then extracting the acetone-free solution with water at 50 to 100 C. whereby the phenol is essentially entirely removed, removing the acetophenone from its solution in the isopropyl benzene by distillation, converting the methyl styrene in the isopropyl benzene into isopropyl benzene by hydrogenation, whereby the puriiied isopropyl benzene may be recycled for further oxidation into isopropyl benzene hydroperoxide, and recovering the phenol from the aqueous solution thereof.

9. In the manufacture of phenol by the oxidation of isopropyl benzene into isopropyl benzene hydroperoxide and the decomposition of said hydroperoxide in its solution in unchanged isopropyl benzene to form a solution containing phenol, acetophenone, acetone and methyl styrene as well as unreacted isopropyl benzene, the process of recovering the latter substantially free from phenol, acetophenone, acetone and methyl styrene, whereby the thus puried unreacted isopropyl benzenemay be recycled for f-urther oxidation into isopropyl benzene hydroperoxide without impairing the efficiency of the oxidation due to prejudicial impurities, said process comprising removing the acetone from said last-named solution by distillation, then extracting the acetone-free solution with water at 50 to 100 C. whereby the phenol is essentially entirely removed, removing the acetophenone and methyl styrene from` the remaining isopropyl benzene solution, whereby the puried isopropyl benzene may be recycled for further oxidation into isopropyl benzene hydroperoxide, and recovering the phenol from the aqueous solution thereof.

l0. In the manufacture of phenol by the oxidation of isopropyl benzene into isopropyl benzene hydroperoxide and the decomposition of said hydroperoxide in its solution in unchanged isopropyl benzene to form phenol, the step of recovering the phenol from said solution containing in addition acetone and methyl styrene which comprises extracting the reaction mixture with water at temperatures between 50 and 100 C. and recovering the phenol from the aqueous extract by contact with butyl acetate, and subsequent distillation.

11. In the manufacture of phenol by the oxidation of isopropyl benzene into isopropyl benzene hydroperoxide and the decomposition of said hydroperoxide in its solution in unchanged isopropyl benzene to form phenol, the step of recovering the phenol from said solution containing in addition acetone and methyl styrene which comprises extracting the reaction mixture with water at temperatures between 50 and 100 C. and recovering the phenol from the aqueous extract by contact with diisopropyl ether, and subsequent distillation.

12. In the manufacture of phenol by the oxidation of isopropyl benzene into isopropyl benzene hydroperoxide and the decomposition of said hydroperoxide in its solution in unchanged isopropyl benzene to form phenol, the step of recovering the phenol from said solution containing in addition acetone and methyl styrene which comprises extracting the reaction mixture with water at temperatures between 50 and 100 C. and recovering the phenol from the aqueous extract by contact with an organic solvent which is substantially immiscible with water and a solvent for phenol, distilling the resulting solvent solution containing phenol and a small quantity of acetophenone to remove the solvent as distillate and leaving as residue phenol with its small admixture of acetophenone, and distilling said residue to recover phenol as distillate.

THOMAS BEWLEY. FREDERICK JOI-IN WILKINS.

References Cited in the file of this patent ,UNITED sTATEs PATENTS Number Name Date 2,199,786 Dierichs et al May 7, 1940 2,339,889 Strickland Jan. 25, 1944 OTHER REFERENCES Hock et al.: Berichte, vol. 77, pages 257-62, 1944. 

5. IN THE MANUFACTURE OF PHENOL BY THE OXIDATION OF ISOPROPHYL BENZENE INTO ISOPROPYL BENZENE HYDROPEROXIDE AND THE DECOMPOSITION OF SAID HYDROPEROXIDE IN ITS SOLUTION IN UNCHANGED ISOPROPYL BENZENE TO FORM PHENOL, THE STEP OF RECOVERING THE PHENOL FROM SAID SOLUTION CONTAINING IN ADDITION ACETONE AND METHYL STYRENE WHICH COM- 